Transformation of animal cells by a variety of tumor viruses leads to significant changes in the growth behavior of transformed cells as well as in some alterations in the antigenic behavior and binding characteristics with plant lectins. These characteristics are believed to be due to chemical and physical changes in the cell surface constituents. The proposed research seeks to study and establish in chemical terms the changes in the membrane structure between untransformed cells and cells transformed by tumor viruses. By labeling specifically the surface components of cells transformed by temperature- sensitive mutants of Polyoma, SV-40 Rous sarcoma virus with radioactive sialic acid and fucose (from the corresponding nucleotide sugars) following the procedure developed by the Principal Investigator, we hope to identify and isolate specific glycoproteins of the cell surface existing under untransformed and transformed phenotypic conditions. Special attention would be given to inquiring whether the number and nature of the labeled surface glycoproteins would change during various growth conditions such as in sparse and crowded cultures, during serum limitation, etc. Using surface-bound radioactive sialic acid and fucose molecules as "reporter" groups we would also study the kinetics of synthesis and turnover of specific glycoproteins during various growth situations. A separate aspect of the study is to investigate the phenomenon of membrane rearrangement resulting from lectin binding, after mild trypsinization and during sparse and density-inhibited growth conditions; for these experiments the labeling patterns of specific surface glycoproteins by sialic acid and fucose would be used as diagnostic probe to assess the nature of the surface alterations both in qualitative and in quantitative terms.